The present invention relates to a fuel cell system and to a method for operating the fuel cell system.
DE 196 24 435 C1 (U.S. Pat. No. 5,928,614) discloses a reforming reactor that is used for the steam reforming of methanol. To stabilize the temperature of the different reactor steps, a heating device is provided for a middle step, while the steps at the inlet side and the outlet side are constructed as heat exchanges. During the methanol reforming reaction, carbon dioxide is formed, which must be removed from the reformate. In general, it is difficult to remove the waste heat developed during a customary, subsequent hydrogen gas shift reaction from the system in order to ensure a balance, thermal equilibrium that has sufficient dynamics.
Pursuant to the present invention, it is possible to work largely without heat exchange during the reforming and the subsequent gas purification. The reforming reactors can be constructed simply and compactly. The manufacturing costs of the reactors can thus be reduced. The system has fewer components and the pressure loss in the gas generating system is reduced.
It is advantageous that the methanol reforming system is very simple and therefore inexpensive. In the reforming region, heat exchangers are not required and, instead, adiabatic reactors can be used. The efficiency is good, especially in low-pressure systems. The system can, however, also be operated in the high-pressure range. A portion of the fuel may contain impurities, since these are broken down in the high-temperature adiabatic reactor. This leads to a savings in costs, since fuels of a lesser purity can be used.
It is to be understood that the aforementioned distinguishing features and those, which are still to be explained below, can be used not only in the combination given, but also in other combinations or by themselves, without leaving the scope of the present invention.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the present invention when considered in conjunction with the accompanying drawings.